>>I know that folks here have traiditionally objected to outside FAQ's
>>when instead the issue could be resolved by dozens of E-mails, but in
>>this case Doug Jone's *PDP-8 Summary of Models and Options* answers
>>the question of 8/E vs 8/F quite nicely:
>Too bad it's wrong.
>It makes it seem as if there was a box that was designated PDP-8/E and it
>had a particular configuration that was retired until the introduction of a
>new box with the designation of PDP-8/F. This isn't supported by the evidence.
Well, that's not how I read it. By my reading, Doug's writeup makes
it perfectly clear that 8/E's and 8/F's were produced simultaneously
and from a common pool of (largely, but not completely) compatible parts.
>What really happened, and I have several independent confirmations of same,
>is that the PDP-8/E system evolved into the PDP-8/F in a series of steps.
>Depending on the date code the machine was configured differently.
And I think that Doug Jone's FAQ entry agrees with you here.
>The evolution vectors were as follows:
> Module updates - example M833 - M8330, M831 - > M8310
In the FAQ, Doug says on this subject:
* Most of the early boards with 3 digit numbers were defective
* in one way or another, and the corrected boards added a trailing
* zero. Thus, the M833 was generally replaced with an M8330, and
* the M865 was replaced with the M8650.
If you look in the PDP8-Lovers/alt.sys.pdp8 archives, you'll find
Charles Lasner going into great detail about the differences between
the different revisions of boards.
> Chassis updates - Long box, single OMNI BUS
> Long box dual OMNI BUS
And in the FAQ Doug agrees with you:
* There were many other internal options. There was room in the
* basic box for another 20 slot backplane; taking into account the
* 2 slots occupied by the M935 bridge between the two backplanes,
* this allowed 38 slots
> Short box single OMNIBUS Linear PSU on side.
> Short box single OMNIBUS Switching PSU in rear.
And again, in the FAQ Doug agrees with you:
* The original PDP-8/F box had a defective power
* supply, but a revised (slightly larger) box corrected this
* problem.
> Front Panel Updates: Diode logic + 8v LAMPS
> TTL logic + 6v LAMPS
> TTL logic + LEDs in lamp sockets
> TTL Logic + LEDS
And again Doug states that there were several front panel configurations.
> PSU updates - Long linear PSU
> Short linear PSU
> Short Switching PSU (types A and B)
And again Doug notes the difference in power supplies.
>At some point in this evolution some marketroid decided to change the name
>from 8/e to 8/f. The OEM version of this platform was called the 8/m and
>included an optional limited function front panel (although all 8/M's I've
>seen so far had the programmers panel but that's only about a dozen so who
>can say)
>
>I happen to have an 8/e that is:
> Short box
> 6v LAMPs plus TTL front panel
> Side mount PSU
There's no doubt that there were many ways to mix and match the
various components produced. I'm a bit uncertain why some folks
try to apply zoology so incessantly to their computers, when in real
life folks move parts between systems with wild abandon, but then
again zoology has always bored me to tears.
>My guess is that the evolution of the 8/E was driven by the introduction of
>the 11/20 since these changes seem have occurred between 1970 and 1972. All
>8/E's with date codes prior to 1970 appear to be the diode front panel
>type, All 8/E's after 1972 appear to be either 8/F's or 8/Ms (until the 8/a
>came out).
Again, I think you're trying too hard to classify machines which were
built from a hodgepodge of parts to fit each individual situation. Lots
of 8/E's and 8/F's went into instruments, and generally the OEM could
pick and choose the features they wanted.
>That being said (and yes I've sent Doug mail on this but its not exactly
>FAQ material unless you really want to restore them as I do) I'd appreciate
>pictures for the cover on the long one since I can fabricate a cover then.
On mine, it's just a big sheet metal panel, with tabes on the right
that go into slots on the chassis and with tape-seal type latches on
the left. No ventilation slots at all. There's a lip on every edge
except for the rear.
--
Tim Shoppa Email: shoppa_at_trailing-edge.com
Trailing Edge Technology WWW: http://www.trailing-edge.com/
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Received on Fri Apr 09 1999 - 21:37:44 BST